Disk Drive Flexure Tail Bond Pad Edge Alignment
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Solution Overview
Problem
In high-volume manufacturing of magnetic hard disk drives, there is a need for an improved design that facilitates automated, rapid, and reliable alignment and electrical connection of conductive traces of a flexure tail to the conductive electrical terminals of a flexible printed circuit, ensuring proper alignment and uniform pressure during the bonding process.
Innovation Solution
The design incorporates a flexure tail terminal region with structural layer discontinuous islands and edge reinforcing islands that facilitate alignment and prevent damage during the bonding process, allowing for automated alignment and pressure transfer, enabling efficient use of anisotropic conductive film bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If automated bonding equipment is used to bond flexure tails to FPC, then productivity and consistency are improved, but the complexity of achieving proper alignment increases
Solution Approach 1:
The flexure tail terminal region incorporates alignment features (edge reinforcing islands and discontinuous islands) that automatically guide and position the flexure tail relative to the FPC during the bonding process. The automated bonding equipment simply needs to apply pressure and heat, while the alignment features self-align the components without requiring complex alignment mechanisms or procedures
Solution Approach 2:
The alignment features act as intermediary elements between the flexure tail and FPC, providing a mechanical interface that ensures proper positioning. The edge reinforcing islands and discontinuous islands serve as intermediate structures that facilitate alignment before the actual bonding occurs
2Reliability
If uniform pressure is applied during bonding, then bonding reliability is improved, but the risk of damage to bond pads increases
Solution Approach 1:
The edge reinforcing islands and discontinuous islands are positioned to provide structural support and cushioning before the bonding pressure is applied. These features distribute the applied pressure uniformly across the bond pad region, preventing concentration of stress that could cause damage while ensuring sufficient pressure for reliable bonding
Solution Approach 2:
The alignment features are strategically positioned at specific locations (edges and corners of the terminal region) to provide localized structural support where needed. The discontinuous islands are placed to reinforce specific areas without covering the entire bond pad region, allowing uniform pressure distribution while maintaining bond pad integrity
3Manufacturing precision
If alignment features are added to the flexure tail terminal region, then alignment precision is improved, but manufacturing complexity increases
Solution Approach 1:
The alignment features are segmented into discrete elements (edge reinforcing islands and discontinuous islands) rather than continuous structures. This segmentation allows for easier manufacturing using standard PCB fabrication processes, as each island can be independently formed through photolithography and etching, while still providing the necessary alignment functionality
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design enhances the alignment and bonding process, ensuring reliable electrical connections while preventing damage and maintaining uniform pressure, thus improving the efficiency and reliability of the bonding process in high-volume manufacturing.
Implementation Method 1
An anisotropic conductive film is typically an adhesive doped with conductive beads or cylindrical particles of uniform or similar diameter. As the doped adhesive is compressed and cured, it is heated and squeezed between the surfaces to be bonded with sufficient uniform pressure that a single layer of the conductive beads makes contact with both surfaces to be bonded. The cured adhesive film may conduct electricity via the contacting beads in a direction normal to the bonded surfaces
Implementation Method 2
the aforementioned electrical connections are made, e.g., by ultrasonic bonding
Data Source
AI summary
A head gimbal assembly for a disk drive includes a flexure having a proximal tongue portion that connects to a head and a flexure tail that extends to a distal flexure tail terminal region. A dielectric layer in the distal flexure tail terminal region is bounded by first and second longitudinal edges. The distal flexure tail terminal region includes a plurality of flexure bond pads in electrical communication with the head. A structural layer of the distal flexure tail terminal region includes a first plurality of discontinuous islands. Each of at least three of the first plurality of discontinuous islands extends over the first longitudinal edge by a protrusion distance. Adjacent ones of the at least three of the first plurality of discontinuous islands are separated by a first longitudinal spacing, measured along the first longitudinal edge, that is no greater than thirty times the protrusion distance.